#!/usr/bin/env python
# -*- coding:utf-8 -*-
# @FileName  :n3_31.py
# @Time      :2020/6/23 14:56
# @Author    :Administrator


def cubic(n):
    sums = 0
    for item in range(1, n + 1):
        sums += item ** 3
    return sums


input_number = int(input("请输入一个数："))
print(cubic(input_number))
